This application claims the priority of Korean Patent Application No. 10-2005-0010181, filed on Feb. 3, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a disk holder for an off-line servo-track writer for writing servo-track information to an information storage disk of a hard disk drive.
2. Description of the Related Art
A hard disk drive (HDD) is one of the information storage devices of a computer and reads data from and writes data onto an information storage disk using a read/write head. When operating, the read/write head is moved to a desired position above a rotating disk by an actuator, floating at a predetermined height from a recording surface of the rotating disk.
In such an HDD, servo-track information is recorded in advance on the surface of the disk so that the read/write head can search a wanted position on the disk and move to the wanted position quickly and precisely. This is called servo-track writing (STW). Generally, servo-track writing is performed after the HDD has been assembled. That is, after one or a plurality of disks are assembled to a spindle motor of an HDD, servo-track information is recorded on the rotating disk.
However, servo-track writing is a time-consuming process. In particular, recently, the data storage capacity of a disk of an HDD has rapidly increased. Accordingly, since the number of tracks of the disk has also increased, the time required for the servo-track writing has become gradually longer, which has increased the manufacturing cost of the HDD.
To solve the above problem, an off-line servo-track writing method is used. In this method, a plurality of disks are installed in a separate off-line servo-track writer so that servo-track writing is performed to the plurality of disks at once. Therefore, the time required for writing servo-track information to the plurality of disks is markedly reduced.
FIG. 1 shows a perspective view schematically illustrating an example of a conventional off-line servo-track writer, and FIG. 2 is a partially sectional view illustrating a disk holder shown in FIG. 1.
Referring to FIG. 1, a driving motor 12 for rotating a plurality of disks 21, a head supporting portion 30 having a plurality of heads for writing servo-track information onto the plurality of disks 21, and a head driving portion 33 for driving the head supporting portion 30 are provided on a bed 11 of an off-line servo-track writer. The plurality of disks 21 are fixed in the disk holder 20 and rotated by the driving motor 12 together with the disk holder 20.
Referring to FIG. 2, the disk holder 20 is fixed to a chuck (not shown) connected to the driving motor 12 and is rotated by the driving motor 12 together with the chuck. To this end, the disk holder 20 is comprised of a hub 24 on which the plurality of disks 21 are fitted, spacers 25 which are fitted around the outer circumference of the hub 24 to keep a set distance between the plurality of disks 21, and a clamp 26 fitted to the end of the hub 24 for fixing the plurality of disks 21 to the hub 24.
In the conventional disk holder 20 configured as described above, there must be a predetermined gap (G) between the outer circumferential surface of the hub 24 and the inner circumferential surfaces of the disks 21 so that the plurality of disks 21 can be easily fitted around the outer circumferential surface of the hub 24. However, due to the gap (G), some of the plurality of disks 21 may be assembled eccentrically with respect to the rotational center of the disk holder 20.
In this case, the positions for recording servo-track information on these disks 21 may differ from each other. Accordingly, when the plurality of disks 21 are installed on the spindle motor of an HDD, phase disparities between individual disks 21 may occur, and repeatable run-out (RRO) occurs when the HDD is operated.